When the volcanic island of Krakatoa erupted in 1883, it "let out a noise louder than any it has made since." Measuring over 172 decibels, it produced "a blast of high pressure air so powerful that it ruptured the eardrums of sailors 40 miles away."

After a peaceful nap three decades long, Mauna Loa seems to be stirring. "While there are no signs of impending eruption, the Hawaiian Volcano Observatory has recorded an increased level of seismic activity on the flanks and summit of Mauna Loa over the past 13 months," reports Big Island Now. "Four distinct earthquake swarms — clusters of earthquakes occurring closely in time and location — have occurred since March 2013."

Mauna Loa is "one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaiʻi in the Pacific Ocean, [and] the largest subaerial volcano in both mass and volume, historically considered the largest volcano on Earth."

As of right now, there is little evidence of deformation or increasing carbon dioxide or sulfur dioxide emissions from Mauna Loa — all key signs that an eruption might be about to start at a shield volcano like Mauna Loa. HVO also notes that the earthquake activity is much less intense now that it was in the years just prior to the 1984 activity. Remember, lava flows from Mauna Loa are definitely a hazard for people living between the volcano and Hilo and Hawaii has been preparing for the volcano’s awakening. Nothing is going on right now, but you can get quite a view from the webcams set up at the Mokuʻāweoweo summit area.

Pyroclastic flows are the infamous deadly avalanches of superheated gas and debris that killed thousands at Pompeii and in the 1902 Mount Pelée eruption on Martinique. Now, thanks to a very brave scientist, you can watch a pyroclastic flow up close.

So, when faced with a pyroclastic flow, why would you try to get up close to one? Julio Cornejo, an INSIVUMEH observer from the Santiaguito volcano observatory (OVSAN), did just that to capture some video (see top and below) that has surprised everyone that has seen it. Cornejo was able to film the very far end of a pyroclastic flow generated by the dome collapse at Santiaguito (see above), when it had lost most of its energy but was still moving. At this point a flow is likely still capable of engulfing and suffocating someone in hot ash and gasses, as happened to many people in the 1902 eruption of Mont Pelee. So, Cornejo is very lucky to have made it out alive with this footage, but what he got was remarkable.

Rudiger Escobar Wolf, a volcanology post-doctoral researcher at Michigan Tech who studies volcanoes in Guatemala, posted a sequence of videos from Cornejo and INSIVUMEH and annotated some of the video to understand what we’re seeing. I’ve also watched the video closely and have two here that show some likely never-before-filmed examples of how pyroclastic flows can be destructive even after they slowed to a snail’s pace relative to their usual speed.

[Video Link] There's a video going around that shows a long line of bison trotting down a road in Wyoming's Yellowstone National Park. Some people are pointing to this as a sign that the animals are hightailing it out of the park because the Yellowstone volcano is about to blow its top. But in the video above, Yellowstone Park Public Affairs Chief Al Nash explains that the bison and other animals are simply migrating to a lower elevation where they can find food, which they do every year in the dead of winter.

Sicily's Mount Etna volcano is currently erupting. The series of explosions began on October 26, but on November 11, the mountain did something rare and nifty. Over the course of several hours it blew out dozens of perfect smoke rings, each hundreds of feet in diameter, including the one pictured here.

It's not the first time Etna has done this. Nobody knows exactly how the rings form, but people have been photographing smoke rings coming from Etna since at least 1970. Volcanologist and tour guide Tom Pfeiffer took this picture, as well as several others that you can see at his Volcano Discovery website. He suspects that the smoke rings are formed when eruptions alter the shape of volcanic vents.

Geology blogger Dana Hunter is putting together some resources that will allow you to take yourself on a fantastic tour of America's most famous volcano. Includes maps, suggested background reading, and routes that will ensure you get to see the most interesting spots on the mountain — and learn stuff while doing it!

At National Geographic, you can read Rowe Findley's 1981 account of surviving the Mount St. Helens eruption — and his deeply moving profiles of many of the people who did not. Includes this seminal quote from 83-year-old Harry R. Truman, who Findley describes as raising "the adjectival use of profanity to a new high": "It's a part of me, and I'm part of that ______ mountain," said Truman. "If I got out of here, I wouldn't live a _____ day, not a ______ day."

It's kind of a "That's no moon" moment in real life — a series of discoveries in the 1960s and 1970s led geologists to realize that most of Yellowstone National Park was one giant volcanic caldera. If you've seen the cable TV specials, you've probably come to the conclusion that an eruption of this supervolcano could doom humanity and that said eruption is bound to happen at any time. But the reality is more nuanced than that, write Annalee Newitz at iO9.com. Not only is a Yellowstone eruption not imminent, but there's also more than one way it could erupt — and the most likely scenarios don't equate to worldwide horror.

It's also a place where Ethiopian men and boys regularly travel in order to cut slabs of salt off of the surface of the Earth and haul them back to civilization. Salt flats like this occur when entire bodies of water totally evaporate. In the Danakil Depression, you'll also find salt towers and other formations caused by evaporation off of volcanic geysers and hot springs.

The photo above was taken by Reuters photographer Siegfried Modola, who traveled with a group of salt miners into the desert and then followed their haul all the way back to the marketplace. You can see his full slideshow of images online. I chose this one because it gives you a view of the salt as it's found on the ground, and the neat, rectangular blocks the merchants cut it into for shipping.

Short answer: We don't know. What makes this story by Erin Wayman interesting is the way it carefully breaks down an almost Hollywood-ready narrative and finds the fascinating uncertainty lurking underneath. The truth is, uncertainty is cool. Because it means there's more stuff left to discover.

On February 20th, 1943, Dionisio Pulido watched as a crack in his farm field collapsed in on itself and began to vomit out ash, rock, and fire. The birth of Mexico's Parícutin volcano is a story I've heard before, but I really enjoyed Dana Hunter's two-part series on the occasion of its 70th volcanaversary. Her posts really get into the perspective of Pulido and other local residents in a way I haven't seen in other accounts, and she does an amazing job of giving you a sense of just how well-documented the birth of this volcano was and why that fact matters so much. Here's Part 1 and Part 2.

The car in this photo was 13 kilometers northeast of Mount St. Helens when that volcano erupted on May 18, 1980. This photo was taken about a month later by researchers from the United States Geological Survey. At the Rosetta Stones blog, Dana Hunter has a really fascinating story — with more eerie photos — about why geologists would want to study totaled vehicles and what we can learn from machines that we can't learn from people.

In 1993, Stanley Williams survived a close-encounter with a volcano. A volcanologist, he was standing on the rim of Colombia's Galeras volcano when it erupted with little warning. Six of his scientific colleagues and three tourists were killed. Williams fled down the mountain's slope — until flying rocks and boulders broke both his legs. With a fractured skull, he managed to stay conscious enough to huddle behind some other large boulders and dodge flying debris until the eruption ended and his grad students rescued him.

Williams and the other scientists were there to study Galeras, and hopefully get a better idea of what signals predicted the onset of eruptions.

This is something we still don't understand well.

While volcanologists have identified some signals — like distinctive patterns of small earthquakes — that increase the likelihood of an oncoming eruption, those signals aren't foolproof predictions. There are still volcanoes like Galeras that give no warning. And volcanoes like Mt. St. Helens. In 2004, that volcano gave signals that it would erupt. And it did. Sort of. The Seattle Times described it as "two small burps and a lava flow". Basically, the signals don't always precede an eruption, and even when they do happen it doesn't tell you much about how big any ensuing eruption will be.

And that presents an interesting question, writes Erik Klemetti at Wired's Eruptions blog. How close to volcanoes should tourists really be? That's a question with real-world applications. This year, New Zealand's White Island volcano has been ... rather grumbly. Even as tourist boats continued to ferry people over for a view of the crater.

There has always been a fragile relationship between volcanoes and tourism. Volcanic features are some of the most fascinating in the world – just look at the millions of people who visit Yellowstone or Crater Lake National Parks for but two examples of hundreds of volcanic tourist attractions around the world (and that doesn’t even consider all the extinct volcanoes or volcanic deposits that can create amazing landscapes as well). However, with the splendor of volcanic features comes the danger that you, as a tourist, are visiting an active volcano. Sometimes, that danger is low, where either the volcano has been dormant for thousands of years, but the signs of magma beneath are still visible. However, the danger can appear to be low in some places but in reality, you are literally putting your lives in the hands of tour operators when you make the visit.

TIL: There is an extinct volcano sitting directly beneath the city of Jackson, Mississippi. Specifically, it is approximately a half mile below the Mississippi Colosseum and state fairgrounds. In the late Cretaceous period — about 100 million years ago — this part of North America was under water. In fact, "North America" back then was actually more like a couple of mini-continents surrounded by ocean. The Jackson Volcano was the heart of a 400-square-mile island in that sea. It hasn't erupted in 65 million years, but the ground is still hot enough that some local wells pump up 102°F water. [Edited to add that the relationship between groundwater temp and the Jackson Volcano may not be accurate. Eric Klemetti — geoscientist and Wired blogger — told me he would be surprised if an extinct volcano was the source of that heat.]

In the 1990s, archaeologists found a mass grave in London, filled with more than 10,000 skeletons. There have been plenty of things over the centuries that could wipe out tons of Londoners en-masse—the Black Death, famine, fires, you name it. But this grave has turned out to be filled with victims of a far more unlikely natural disaster. Scientists now think those people were killed by a volcano.

Not a volcano in England, of course. But a massive eruption thousands of miles away.

Scientific evidence – including radiocarbon dating of the bones and geological data from across the globe – shows for the first time that mass fatalities in the 13th century were caused by one of the largest volcanic eruptions of the past 10,000 years.

Such was the size of the eruption that its sulphurous gases would have released a stratospheric aerosol veil or dry fog that blocked out sunlight, altered atmospheric circulation patterns and cooled the Earth's surface. It caused crops to wither, bringing famine, pestilence and death.

Mass deaths required capacious burial pits, as recorded in contemporary accounts. In 1258, a monk reported: "The north wind prevailed for several months… scarcely a small rare flower or shooting germ appeared, whence the hope of harvest was uncertain... Innumerable multitudes of poor people died, and their bodies were found lying all about swollen from want… Nor did those who had homes dare to harbour the sick and dying, for fear of infection… The pestilence was immense – insufferable; it attacked the poor particularly. In London alone 15,000 of the poor perished; in England and elsewhere thousands died."

So, say you're an Icelandic tour company, with access to an extinct volcano (or, at least, a volcano that hasn't erupted in 4,000 years). And say you want to offer tours inside of said volcano, to tourists who don't have the rappelling experience to get themselves down and up the steep sides of the volcano's crater. How do you do it?

We use a system normally used to carry window cleaners outside of skyscrapers, an open elevator system. A basket that holds 5-6 persons is connected to a crane that has been placed vertically over the crater opening. Massive cable wires move the basket up and down the bottle-shaped vault. The 120 m/400 ft journey takes about 10 minutes to complete.

There are few things quite as tense as watching one volcanologist mutter, "Oh my god. He's crazy. He's crazy," while watching another volcanologist scramble around the edge of a caldera.

It only gets more tense when you realize that the volcano in question is Nyiragongo in the Democratic Republic of the Congo—which has some of the fastest-moving lava flows ever recorded. The key feature of Nyiragongo is that lake of lava in the center of the crater that you see in the video. In January 1977, the lava lake was 2000 feet deep. When the volcano erupted later that month, the lake emptied dry in less than an hour. Lava was clocked at 40 mph.

Here's a story that combines two favorite bits of volcano news into one interesting discovery. You know those great, freaky photos of volcanic lightning? (In case you don't, I've got one posted above.) Remember how the Icelandic volcanic eruptions totally screwed up everybody's airplane travel plans?

Apparently, studying volcanic lightning could lead to better eruption detection systems that could make it easier to predict how big a plume of ash off that volcano will be—knowledge that can help airlines and travelers be better prepared. At Nature, Richard Monastersky reports:

The researchers found that the amount of lightning correlated with the height of the plume, something they could not test using more limited data collected during an eruption at Alaska’s Mount St Augustine in 2006. This observation is important, says Behnke, because systems to monitor lightning could provide an estimate for the size of an eruption, which is not always easy to assess for remote volcanoes.

During a previous eruption at Mount Redoubt in 1989 and 1990, for example, the size of the plume wasn’t known and a plane nearly crashed after passing through the ash cloud and temporarily losing all power from its engines. Behnke and her colleagues suggest that VHF stations similar to the ones they installed at Mount Redoubt could be used to monitor volcanoes to give early warning of an eruption and an estimate of its size.

Plinian eruptions are named after Pliny the Younger and Pliny the Elder, who wrote about the eruption of Mount Vesuvius in AD 79 and died during said eruption, respectively. This is one of several different types of volcanic eruptions, but it's also one of the most iconic. In a Plinian eruption, a column of magma, gas, and ash shoots straight up, with the gas and ash reaching all the way up into the stratosphere. These are the big, explosive eruptions, with mushroom clouds and rains of rocks and boulders.

Matt Kuchta, geology professor at the University of Wisconsin Stout, recently recreated a classic Plinian eruption using a 32-gallon trash can filled with water, 100 rubber ducks, and some liquid nitrogen. In slow motion, you can see the column of water and ducks rise straight up, fan out at the top, and fall back down to Earth. Just imagine the damage if all the ducks were boulders, and you get the picture.

On December 13, fishermen in the Red Sea reported volcanic eruptions shooting lava into the air. Just ten days later, the new island was visible. Volcanic island formation is one of those natural phenomena that most of us have known about since grade school. And yet, it never becomes not awesome. Smithsonian has a Q&A with volcanologists (still one of the most awesome jobs), that explains some of what's going on. Even if you already know the general basics, the specifics of this particular island are pretty neat.

The “new” volcano, of which you can see the very top, has probably been erupting episodically underwater for thousands of years. While its above-surface dimensions are roughly 1,739 feet east-to-west and 2,329 feet north-to-south we know the larger submerged shield it sits on is about 12.5 miles across—an edifice whose age is unknown, but the Red Sea may have begun spreading apart about 34 million years ago and the shield volcano could thus be tens of millions of years in the making.

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Keep in mind that this whole region has had many volcanic eruptions in the last five years. In 2007, for example, a sudden eruption on the nearby Island Jebel at Tair killed a number of soldiers stationed there. The process of plate tectonics seems to be going on a little faster, at a quickened rate in this area. Why? We don’t know. The general public needs to be reminded that volcanologists are often in the dark about these processes.